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How to activate heavy duty trailer wiring

TIDALWAVE

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My JL Rubi came with the heavy duty trailer wiring. Combo 4 conductor outlet and 7 conductor outlet. The outlets don't have power! I have 4 and 7 conductor testers and neither register any power.
The user manual simply assumes that there is power being fed to the rear...it is not!

The factory installed 20A/30A fuses are not standard blade fuses but are double sized 'box' fuses with blue tops.

Has anyone else had this problem with the JL heavy duty trailer package?

Does the trailer system have to be 'initialized' through the UConnect programming?
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dgreen1069

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I have not tested my 4-pin connector, but the 7-pin is active including the constant 12-volt charge line. I didn't need to add any fuses to make it work.
 

InvertedLogic

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I've towed a u-haul with the 4-pin connected with no issues and no "initialization" required. Sounds like you have a broken connection somewhere?
 

word302

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I would check the connector back where the plug fixture plugs in to the harness? Check every fuse as well.
 

phranque1673

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Was this orderd as part of the build, or did the dealer install after the fact?

Dealer installed does not use the fuse box.
 

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JP18

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The only wire that is "activated" at idle (engine on) is the always-on hot 12V in the 7-pin connector, and both grounds in the 7-pin and the 4-pin. Turning on the headlights will turn on the parking/position wires in both the 4 & 7-pins. Applying the brakes will send power to the brake pins (1 L, 1 R) in both the 4 & 7 pins.

How were you checking the connectors? Engine on? brakes / lights on? or?

For the electric brakes to work on the 7-pin, you will need a brake controller as the JL do not come with a built-in controller. (Some heavier duty pickups do come with them nowadays but 10 years back, most didn't).

Also note that there are 3 "brakes" wires on the 7-pin, two for the brake lights and one for the electric brakes.

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phranque1673

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Is it the same harness but wired differently? Thanks.
Yes, the images I have seen show that the fuses are external to the fuse box when the dealer installs the kit as they cannot add wires to the fuse box. This may just be for the aux switches though. Mine was dealer installed and works fine.
 

pstallin

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Tidalwave did you ever get tyour problem resolved?

I am wiring in additional backup lights to the trailer light wires and am having the same problem, ie no voltage to the reverse wire when the jeep is in reverse.

I haven't checked the fuses yet as I just learned there were separate fuses for the HD trailer add on and it's now dark outside.
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